The present invention relates to a yarn package winding apparatus in general, and more particularly to an arrangement for holding a bobbin tube while yarn is being wound on such tube during a winding operation.
There are already known many constructions of yarn package winding apparatus which are used, for example, in conjunction with yarn spinning machines, especially rotor, jet, friction and wrap spinning machines, yarn rewinding machines and false twist texturizing machines. The yarn packages formed by such winding apparatus may be cylindrical (cheeses) or frusto-conical (cones).
In such apparatus, it is a common practice to use a so-called cradle to support the package during its formation. Such a cradle usually comprises a pair of arms which are adapted to support the respective bobbin tube between them, these arms being jointly pivotable about a common axis which has a fixed position with respect to a machine frame during the package winding operation.
The yarn which is supplied to the winding apparatus is wound onto the bobbin tube supported on the cradle to gradually build up the package on the bobbin tube. This is achieved by causing the bobbin tube to rotate about its longitudinal axis while traversing the yarn to-and-fro across the traverse region which extends in the longitudinal direction of the bobbin tube and is coextensive with the axial length of the package, at a speed which is selected on the basis of the linear delivery speed of the yarn to give a desired pitch to the yarn convolutions of the package. The rotation of the tube and of the package being formed thereon is normally effected by a frictional contact initially of the tube and subsequently of the package being formed thereon with a driven friction roller which is rotatably supported on the machine.
Arrangements of this type are quite well known in the yarn processing field. Examples of such arrangement may be found, for instance, in the British Patent Specification No. 1,349,425 (cheeses), published European Patent Application No. 0128417 (cheeses), U.S. Pat. No. 4,415,125 (cones), U.S. Pat. No. 3,139,239 (cones) and British Patent Specification No. 1,344,226 (adjustably settable either for cones or for cheeses). However, many other patents and publications also disclose similar arrangements.
The aforementioned arms of the cradle usually assume a first relative position in which a bobbin tube of an approximately predetermined dimension can be retained between the arms while being free to rotate about its longitudinal axis, and a second position in which the tube is released for removal, usually after a package has been formed thereon, to enable its replacement by a fresh tube in preparation for the next following winding operation. For this purpose, one or both of the arms may be movably mounted on a common support which moves with these arms about the common axis which has been mentioned above. The movement of the respective arm between its first and second relative positions with respect to the other arm may be a pivotal movement about an axis which extends transversely with respect to the common axis. Such an arrangement is also well known in the textile field, as exemplified, for instance, by the British Patent Specification No. 1,588,814.
There is a well-known problem associated with all previous arrangements of this type, namely, the achievement of an adequate positional stability of the package and its support in spite of the occurrence of vibrations which inevitably arise when the drive systems mentioned above are being used. To avoid this problem, it has already been proposed to damp such vibrations, and damping systems involving frictional contact between a part movable with the arms and a part supported on the machine have been disclosed, for instance, in the published German Patent Specification Nos. 1,560,611 and 3,421,650, in U.S. Pat. No. 3,883,082, in the British Patent Specification No. 1,407,576 and in the U.S. Pat. Nos. 2,605,974 and 3,733,034. However, these arrangements still suffer from certain defects, especially the interference of the vibration damping arrangement with the opening and/or closing movements of the arms.